Add orbit repository reference

Author: adangel

net.sourceforge.pmd.eclipse.p2updatesite/category.xml

@@ -8,4 +8,5 @@
          PMD Plugin for Eclipse
       </description>
    </category-def>
+   <repository-reference location="http://download.eclipse.org/tools/orbit/downloads/drops/R20140114142710/repository/" enabled="true" />
 </site>